Is 2 gallons enough? IMO I don't' think its enough. Why? because your not going to fill it up to the top
Can I get away with just an airrator? No, I pier fish as well and I put about five in my 5 gallon bucket with an airrator and they just end up dead.
What size pump should I use? Is this a stupid idea?
http://www.kayakfishingsupplies.com/...-360gph/Detail
this should help you out with an idea.
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Cool looking bag. How bout getting a 5 gallon bucket and cutting to fit that bag.
To have it flush so you can close it when transporting. You can place an out take threw the bottom mating it with the scuffer holes. Just to start you off.